This set of Rocket Propulsion Multiple Choice Questions & Answers (MCQs) focuses on “Liquid Propellant Rocket Engine – Tank Pressurization”.
1. Tank pressure for the pressure feed system is between ___________ and __________
a) 100 psi; 2000 psi
b) 200 psi; 1800 psi
c) 300 psi; 2400 psi
d) 800 psi; 3000 psi
Explanation: Tank pressure for the pressure feed system lies between 200 and 1800 psi. 1 psi is about 6894.76 Pa. For pump fed systems, the tank pressure lies between 10 and 50 psi.
2. Which of the following gases cannot be used for gas pressure feed systems?
Explanation: Inert gases are used in gas pressure feed systems. Ozone is not an inert gas. Hence it cannot be used in this case.
3. Pump feed systems don’t require positive pressure in the tank.
Explanation: Pump feed systems require a small positive pressure in the tanks to suppress pump cavitation. When it happens, it will lead to the formation of small vapor bubbles in the pump and subsequent collapse or implosion of it, damaging the pump.
4. Which of the following is not true about the pressurizing gas?
a) It shouldn’t be soluble in the liquid propellant
b) It shouldn’t condense in the presence of the liquid propellant
c) It should be inert
d) It should have at least 10% moisture content
Explanation: The pressurizing gas should be dry and shouldn’t contain any moisture. Else the moisture might react with the propellant or might dilute it.
5. Propellant tanks containing oxygen and nitrogen tetroxide can be pressurized using _________
a) helium and nitrogen respectively
b) nitrogen and helium respectively
c) helium alone
d) nitrogen alone
Explanation: Nitrogen will react with oxygen and nitrogen tetroxide and decrease the density and concentration of the oxidizer. In order to avoid that, helium is used instead of nitrogen for pressurizing the tanks containing oxygen or nitrogen tetroxide.
6. For pressurizing cryogenic propellant tanks, the amount of gas required is _________ compared to an equivalent tank containing a non-cryogenic propellant.
d) not related in any way
Explanation: A larger mass of the gas will be required in the cryogenic case. This is because the gas will be warmer compared to the cryogenic propellant and it will cool down increasing its density.
7. Which of the following pressurization techniques involves combustion inside the propellant tank?
a) Chemical pressurization
b) Gas fed pressurization
c) This is not possible
d) Dynamic pressurization
Explanation: Chemical pressurization involves the injection of fuel or other suitable igniting material to cause combustion inside the propellant tank to produce gases to pressurize the tank. This is a small and light pressurization technique, but it doesn’t often produce reproducible tank pressures.
8. Pressurizing gas cannot perform ___________
a) operation of valves
b) operation of controls
c) admission of propellants into the tank
d) expulsion of propellants away from the tank
Explanation: In some systems, pressurizing gases can operate valves and controls. But the main duty of pressurizing valves is the expulsion of propellants away from the tank.
Sanfoundry Global Education & Learning Series – Rocket Propulsion.
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